1. Field of the Invention
The present invention relates to an image forming device and a fixing unit.
2. Description of Related Art
Electrophotographic image forming devices, such as laser printers, are equipped with a light-emitting unit including a laser diode and the like for emitting a light beam, and a photosensitive member, the surface of which bears a uniform charge. When the surface of the photosensitive member is exposed to the light beam, electrostatic latent images are formed on the surface of the photosensitive member and the latent images are then developed into visible images with toner. Subsequently, the visible images are transferred onto a paper or other recording medium to form visible toner images on the recording medium.
However, the images transferred onto the recording medium are merely fixed to the recording medium by an electrostatic force or dispersion force and can easily come off the recording medium. Therefore, a fixing process is required to fix the visible images to the recording medium through a process of applying heat or the like.
A fixing device provided in the image forming device for fixing images using heat typically include a heating roller and a pressure roller that serve as fixing rollers. As the recording medium passes between the heating roller and the pressure roller, the toner or other developing material is sintered and coalesced by the heat from the heating roller, so as to permeate and become fixed to the recording medium. The heating roller accommodates a heat source, such as a halogen lamp. Since failure or the like of the halogen lamp is fatal to the image forming device, resulting in a loss of the fixing function, the fixing unit need to be easily replaceable. Various proposals, such as that described in Japanese patent-application publication No. HEI-8-305205, have been made for fixing units integrally configured of a heating roller, pressure roller, and the like that can easily be replaced when malfunctions occur.
Since it is convenient for users of common household printers to be able to install their printers in a small space, such as on a bookshelf, there is a large demand for compact laser printers and other image forming devices. However, in order to facilitate replacement of the fixing unit, as described above, a space inside the device through which the fixing unit can be removed must be secured, as illustrated in FIG. 8 of Japanese patent-application publication No. HEI-7-210023. This makes it difficult to reduce the sizes of devices, and particularly to reduce the height.